JP6925448B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner provided with an inrush current limiting circuit.

Conventionally, in an air conditioner, an inrush current limiting circuit composed of an inrush current limiting resistor and a relay has been used as a circuit for limiting the inrush current when power is input from a commercial AC power source.

For example, in Patent Document 1, the inrush current limiting circuit is reliably operated by setting the relay contact to be open in the standby state of the device, thereby solving the problem that the device does not operate due to the failure of the relay. There is. Further, in Patent Document 1, a relay control is used that eliminates the power loss caused by the operating current after the operation of the device by short-circuiting the relay contacts when a certain time elapses after the power is turned on from the commercial AC power supply.

In Patent Document 1, the resistance value of the inrush current limiting resistance for limiting the inrush current is limited so as to satisfy the pulse limit power without imposing an excessive load on the elements and devices inside the rectifying smoothing circuit. It is selected so that the resistance itself is not destroyed and the value satisfies the rated power.

JP-A-2010-104109

However, when the relay control method is adopted so that the relay contact is opened when the device is on standby as described above, the inrush current limiting resistance generates heat when an abnormal voltage is applied to the inrush current limiting circuit. The resistance value of the inrush current limiting resistor may not return to the normal value. In that case, there is a problem that the inrush current limiting circuit does not operate normally when the operation is started from the standby state, and the air conditioner does not operate and the operation cannot be performed.

The present invention has been made in view of the above, and an object of the present invention is to obtain an air conditioner capable of realizing stable operation even when a resistor constituting an inrush current limiting circuit generates heat.

In order to solve the above-mentioned problems and achieve the object, the present invention has first and second input terminals, and the second input terminal is connected to a commercial AC power supply, and the first and second input terminals are connected. A converter unit that converts the first AC voltage input from the input terminal of the above into a DC voltage and outputs it, a plurality of resistors connected between the commercial AC power supply and the first input terminal, and a plurality of resistors. It includes an inrush current limiting circuit having a plurality of relays capable of short-circuiting or opening both ends of each device, and an inverter unit that converts the DC voltage output by the converter unit into a second AC voltage and supplies it to the motor. Further, the present invention is used to compare the temperature with the threshold value after receiving the signal related to the operation of the motor and the temperature detection unit for detecting the temperature of the resistor and before operating the converter unit and the inverter unit. A control unit that executes control of the relay based on the control is provided.

The air conditioner according to the present invention has an effect that stable operation can be realized even when the resistance constituting the inrush current limiting circuit generates heat.

Block diagram of an air conditioner including an inrush current limiting circuit according to an embodiment of the present invention. Flow chart explaining the operation of the air conditioner according to the embodiment A block diagram showing a configuration of a microcomputer according to an embodiment.

Hereinafter, the air conditioner according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment.
FIG. 1 is a block diagram of an air conditioner 100 provided with an inrush current limiting circuit 8 according to an embodiment of the present invention. The air conditioner 100 is supplied from the inrush current limiting circuit 8 for limiting the inrush current, the temperature detection unit 9 for detecting the temperature of the inrush current limiting resistor of the inrush current limiting circuit 8, and the commercial AC power supply 1. The converter unit 13 that converts the AC power of 1 into DC power, the inverter unit 14 that converts the DC power supplied from the converter unit 13 into the second AC power and supplies it to the motor 21, the motor 21, and the relay coil. It includes a drive circuit 15, a microcomputer 50 as a control unit, and a power supply circuit 22.

The inrush current limiting circuit 8 includes a resistor 2 and a resistor 5 connected in series for inrush current limiting, and a relay 4 and a relay 7. The resistor 2 and the resistor 5 are resistors for limiting the inrush current instantaneously applied when the power is turned on from the commercial AC power supply 1. The relay 4, which is the first relay, is composed of a relay contact 30 connected in parallel to the resistor 2 which is the first resistor, and a relay exciting coil 3 which controls the opening and closing of the relay contact 30. Both ends of the relay contact 30 are connected to both ends of the resistor 2, respectively. The state in which the relay contact 30 is closed and both ends of the resistor 2 are short-circuited is defined as the closed state of the relay 4, and the state in which the relay contact 30 is opened and both ends of the resistor 2 are opened is defined as the open state of the relay 4. The relay 7 which is the second relay is composed of a relay contact 60 which is connected in parallel to the resistor 5 which is a second resistor and a relay exciting coil 6 which controls the opening and closing of the relay contact 60. Both ends of the relay contact 60 are connected to both ends of the resistor 5, respectively. The state in which the relay contact 60 is closed and both ends of the resistor 5 are short-circuited is defined as the closed state of the relay 7, and the state in which the relay contact 60 is opened and both ends of the resistor 5 are opened is defined as the open state of the relay 7. The relay coil drive circuit 15 drives the relay excitation coils 3 and 6, so that the open / closed states of the relays 4 and 7 are controlled. The number of resistors included in the inrush current limiting circuit 8 is not limited as long as they are present, and the number of resistors may be parallel connection or a combination of series connection and parallel connection instead of series connection.

Further, the temperature detection unit 9 specifically detects the temperatures of the resistor 2 and the resistor 5, respectively.

A specific example of the resistor 2 and the resistor 5 is a thermistor having a positive temperature coefficient, that is, a PTC (Positive Temperature Coefficient) thermistor. Having a positive temperature coefficient is a resistance change characteristic in which the resistance value increases with increasing temperature. The PTC thermistor is a thermistor in which when the temperature exceeds the Curie temperature determined for each thermistor, the resistance value rapidly increases with respect to the temperature rise and no current flows. At least one of the plurality of resistors included in the inrush current limiting circuit 8 may be a thermistor having a positive temperature coefficient.

The converter unit 13 includes a first input terminal 131, a second input terminal 132, a first output terminal 133, a second output terminal 134, a booster circuit 10, a diode bridge 11, and a smoothing capacitor 12. A resistor 2 and a resistor 5 are connected between the first input terminal 131 and the commercial AC power supply 1, and the second input terminal 132 is connected to the commercial AC power supply 1. The resistor 2 and the resistor 5 may be connected between the second input terminal 132 and the commercial AC power supply 1, and the first input terminal 131 may be connected to the commercial AC power supply 1. The converter unit 13 converts the first AC voltage given from the first input terminal 131 and the second input terminal 132 into a DC voltage and outputs it to the first output terminal 133 and the second output terminal 134. The inverter unit 14 converts the DC voltage output by the first output terminal 133 and the second output terminal 134 of the converter unit 13 into a second AC voltage and supplies the DC voltage to the motor 21.

The microprocessor 50 is driven by a dedicated power supply circuit 22. The user can operate a remote controller (hereinafter referred to as a remote controller) (hereinafter, referred to as a remote controller) (hereinafter referred to as a remote controller), and the microcomputer 50 maintains the remote controller standby state until a remote controller operation is input from the user. The microcomputer 50 includes a relay control unit 16 that controls the relay coil drive circuit 15, a remote control control unit 17 that receives a remote control signal that is a signal from the remote control operated by the user's remote control, and a detection temperature detected by the temperature detection unit 9. A temperature determination unit 18 for executing temperature determination based on the above is provided. The remote control signal is a signal related to the operation of the motor 21 such as operation start, operation stop, heating start, and cooling start. The remote control standby state is a state in which the microcomputer 50 can receive the remote control signal.

When the power from the commercial AC power supply 1 is supplied at the start of operation of the air conditioner 100, the inrush current limiting circuit 8 limits the current by a resistor corresponding to the relay in the open state. However, since the relays 4 and 7 are in the open state when the air conditioner 100 is stopped, the resistance value of the resistor 2 may increase due to heat generation and no current may flow when an abnormal voltage is applied. In this case, if the air conditioner 100 starts operation from the stopped state while the relay 4 is in the open state, the voltage is not applied from the inrush current limiting circuit 8 to the subsequent circuit.

Therefore, in the air conditioner 100 according to the present embodiment, when the remote control signal is input to the remote control control unit 17 by the remote control operation of the user, the temperature detection unit 9 detects the temperature of the resistor 2. , The temperature determination unit 18 of the microcomputer 50 executes the temperature determination. Then, when the temperature determination unit 18 determines that the temperature of the resistor 2 detected by the temperature detection unit 9 is larger than the first threshold value set for the resistor 2, the relay control unit 16 tells the relay coil drive circuit 15 A signal instructing the relay excitation coil 3 to be driven is output, and the relay coil drive circuit 15 controls the relay 4 to be in a closed state.

That is, when an abnormal voltage is applied while the air conditioner 100 is stopped and the operation is started from the stopped state with the resistor 2 generating heat, the relay 4 is controlled to the closed state, so that the inrush current Since the limiting circuit 8 uses only the resistor 5, the operation of the air conditioner 100 can be started with the inrush current limited.

FIG. 2 is a flowchart illustrating the operation of the air conditioner 100 according to the embodiment. Hereinafter, the operation of the air conditioner 100 will be described with reference to FIG.

First, the microcomputer 50 driven by the dedicated power supply circuit 22 is in the remote control standby state (step S11). The remote control control unit 17 of the microcomputer 50 determines whether or not a remote control signal is received by the user's remote control operation (step S12). If the remote control signal has not been received (step S12: No), the process returns to step S11.

When the remote control control unit 17 determines that the remote control signal has been received (step S12: Yes), the temperature determination unit 18 determines whether or not the temperature of the resistor 2 detected by the temperature detection unit 9 is equal to or lower than the first threshold value. (Step S13). The first threshold value is a value determined by the element temperature characteristic of the resistor 2, the operable temperature data of the resistor 2, the failure temperature of the resistor 2, and the like, and is stored in advance in the storage unit of the microcomputer 50. There is.

When it is determined that the temperature of the resistor 2 which is the first resistor is higher than the first threshold value (step S13: No), the relay control unit 16 sends a signal to the relay coil drive circuit 15 to send a signal to the first relay. The relay 4 is controlled to be in the closed state (step S14). On the other hand, when the temperature of the resistor 2 is determined to be equal to or lower than the first threshold value (step S13: Yes), and after step S14, the remote control control unit 17 indicates that the received remote control signal "starts operation". It is determined whether or not it is a signal (step S15).

When it is determined in step S15 that the received remote control signal is a signal instructing "start of operation" (step S15: Yes), the air conditioner 100 starts operation (step S16). Specifically, the microcomputer 50 operates the converter unit 13 and the inverter unit 14. After step S16, the temperature determination unit 18 determines whether or not the temperatures of the resistors 2 and 5, which are the first and second resistors detected by the temperature detection unit 9, are both equal to or lower than the second threshold value ( Step S17). The second threshold value is a value determined by the element temperature characteristics of the resistors 2 and 5, the operable temperature data of the resistors 2 and 5, the failure temperature of the resistors 2 and 5, and the like, and is stored in the microcomputer 50. It is held in advance in the unit. The second threshold value may be the same value as or different from the first threshold value.

On the other hand, in step S15, when it is determined that the received remote control signal is not a signal instructing "start of operation" as in the case of a signal instructing "stop operation" (step S15: No), the relay control unit. 16 sends a signal to the relay coil drive circuit 15 to control the relays 4 and 7, which are the first and second relays, to be in the open state together (step S19). After step S19, the air conditioner 100 stops operation (step S20) and returns to the remote control standby state (step S11).

When it is determined in step S17 that the temperatures of the resistors 2 and 5 are both equal to or lower than the second threshold value (step S17: Yes), the relay control unit 16 sends a signal to the relay coil drive circuit 15, and the first step is The second relays, relays 4 and 7, are both controlled to be in the closed state (step S18). If the relay 4 is already in the closed state via step S14, the relay 7 is further controlled to be in the closed state. After step S18, the process returns to the remote control standby state (step S11).

As described above, when it is determined that the detected temperature of the resistor 2 is higher than the first threshold value (step S13: No), the relay 4 is kept in the closed state (step S14). As a result, since the inrush current limiting circuit 8 uses only the resistor 5, the operation of the air conditioner 100 can be started in the state where the inrush current is limited (step S16). Then, after the operation of the air conditioner 100 is started, when it is determined that the temperatures of the resistors 2 and 5 are both equal to or lower than the second threshold value (step S17: Yes), the relays 4 and 7 are both closed. (Step S18). As a result, the power from the commercial AC power supply 1 can be supplied to the converter unit 13 without going through the resistors 2 and 5 which are inrush current limiting resistors, so that the air conditioner 100 can be operated with maximum efficiency. It becomes possible to make it.

On the other hand, in step S17, when it is determined that any of the temperatures of the resistors 2 and 5 is larger than the second threshold value (step S17: No), the relay control unit 16 sends a signal to the relay coil drive circuit 15. Control is performed so that the relays 4 and 7, which are the first and second relays, are both in the open state (step S19). After step S19, the air conditioner 100 stops operation (step S20) and returns to the remote control standby state (step S11).

In step S13, the temperature determination unit 18 determines whether or not the temperature of the resistor 2 is equal to or lower than the first threshold value, but when the temperature of the resistor 5 is larger than the threshold value in comparison with the threshold value. The relay 7 may be controlled to be in the closed state. The resistor to be short-circuited in step S14 after the temperature is determined to be larger than the threshold value in step S13 may be selected because the resistance value is larger than that of the other resistor. This is because if the resistance value is larger than that of the other resistor, the temperature is likely to rise due to energization.

In the above description, the user performs the operation via the remote controller, but the controller of the air conditioner 100 may be installed in the main body of the air conditioner 100. Therefore, the microcomputer 50 may be provided with an operation control unit instead of the remote control unit 17, and the operation control unit may be configured to determine in step S12 whether or not a signal related to the operation of the motor 21 has been received. ..

As described above, in the air conditioner 100 provided with the inrush current limiting circuit 8, a relay is relayed based on the temperature of the resistors 2 and 5 constituting the inrush current limiting circuit 8 when the user operates the remote controller. Controls 4 and 7. As a result, even if an abnormal voltage is applied when the operation of the air conditioner 100 is stopped, the inrush current avoids the malfunction at the start of operation due to the heat generation of the inrush current limiting resistor when the relay contact is opened. Can be restricted. In addition, it is possible to prevent failures due to element heating during operation, and stable operation can be realized.

FIG. 3 is a block diagram showing the configuration of the microcomputer 50 according to the embodiment. The microcomputer 50 includes a CPU (Central Processing Unit) 51 that executes arithmetic and control, a RAM (Random Access Memory) 52 that the CPU 51 uses for a work area, a ROM (Read Only Memory) 53 that stores programs and data, and the like. It includes an I / O (Input / Output) 54, which is hardware for exchanging signals with the outside, and a peripheral device 55 including an oscillator that generates a clock. The control executed by the relay control unit 16, the remote control unit 17, and the temperature determination unit 18 of the microcomputer 50 according to the flowchart shown in FIG. 2 is realized by the CPU 51 executing a program that is software stored in the ROM 53. .. The ROM 53 may be a non-volatile memory such as a rewritable flash memory. Therefore, the storage unit of the microcomputer 50 that stores the first and second threshold values is realized by the ROM 53 or the like.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 Commercial AC power supply, 2,5 resistor, 3,6 relay exciting coil, 4,7 relay, 8 inrush current limiting circuit, 9 temperature detector, 10 booster circuit, 11 diode bridge, 12 smoothing capacitor, 13 converter , 14 Inverter unit, 15 Relay coil drive circuit, 16 Relay control unit, 17 Remote control unit, 18 Temperature determination unit, 21 Motor, 22 Power supply circuit, 30, 60 Relay contacts, 50 Microcomputer, 51 CPU, 52 RAM, 53 ROM, 54 I / O, 55 peripherals, 100 air conditioner, 131 first input terminal, 132 second input terminal, 133 first output terminal, 134 second output terminal.

Claims (4)

It has first and second input terminals, the second input terminal is connected to a commercial AC power supply, and the first AC voltage input from the first and second input terminals is converted into a DC voltage. The converter section that converts and outputs,
An inrush current limiting circuit having a plurality of resistors connected between the commercial AC power supply and the first input terminal, and a plurality of relays capable of short-circuiting or opening both ends of the plurality of resistors. ,
An inverter unit that converts the DC voltage output by the converter unit into a second AC voltage and supplies it to the motor.
A temperature detector that detects the temperature of the resistor and
A control unit that executes control of the relay based on a comparison between the temperature and the threshold value after receiving a signal related to the operation of the motor and before operating the converter unit and the inverter unit.
Air conditioner equipped with. The plurality of resistors are a first resistor and a second resistor connected in series.
When the temperature of the first resistor is higher than the first threshold value after receiving the signal and before operating the converter unit and the inverter unit, the control unit may perform the first method. The air conditioner according to claim 1, wherein the relay is controlled so as to short-circuit both ends of the resistor. After short-circuiting both ends of the first resistor because the temperature of the first resistor is higher than the first threshold value, the control unit of the first resistor and the second resistor The air conditioner according to claim 2, wherein the relay is controlled so as to short-circuit both ends of the second resistor when the temperature is equal to or lower than the second threshold value. The air conditioner according to any one of claims 1 to 3, wherein at least one of the plurality of resistors is a thermistor having a positive temperature coefficient.

Images